Compounds having a 3-aminopyrazol[4,3-c]quinolin-2-one skeleton are unknown. 3-Amino-6,7,8,9-tetrahyiropyrazolo[4,3-c]quinolin-4-one derivatives represented by formula: ##STR2## wherein R represents a hydrogen atom or a methyl group, which are deemed structurally relevant to the compounds of the present invention are described in Journal of Chemical Society, Pirkin I, p. 857 (1978), but their pharmacological activities are entirely unknown.